Two low-lying neutron-unbound excited states of 24 O, populated by proton-knockout reactions on 26 F, have been measured using the MoNA and LISA arrays in combination with the Sweeper Magnet at the Coupled Cyclotron Facility at the NSCL using invariant mass spectroscopy. The current measurement confirms for the first time the separate identity of two states with decay energies 0.51(5) MeV and 1.20(7) MeV, and provides support for theoretical model calculations, which predict a 2 + first excited state and a 1 + higher energy state. The measured excitation energies for these states, 4.70(15) MeV for the 2 + level and 5.39(16) MeV for the (1 + ) level, are consistent with previous lower-resolution measurements, and are compared with five recent model predictions.

The Event Plane Detector (EPD) is an upgrade detector to the STAR experiment at RHIC, designed to measure the pattern of forward-going charged particles emitted in a high-energy collision between heavy nuclei. It consists of two highly-segmented discs of 1.2-cm-thick scintillator embedded with wavelength-shifting fiber, coupled to silicon photomultipliers and custom electronics. We describe the general design of the device, its construction, and performance on the bench and in the experiment.

We present a comprehensive account of the proton radiation hardness of Eljen Technology's EJ-500 optical cement used in the construction of experiment detectors. The cement was embedded into five plastic scintillator tiles which were each exposed to one of five different levels of radiation by a 50 MeV proton beam produced at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. A cosmic ray telescope setup was used to measure signal amplitudes before and after irradiation. Another post-radiation measurement was taken four months after the experiment to investigate whether the radiation damage to the cement recovers after a short amount of time. We verified that the radiation damage to the tiles increased with increasing dose but showed significant improvement after the four months time interval.

n/a